You will want to double check the IP address and the port number of the server. Check if you can access that server in the local network. If you are unable to access the server in your local network, please check settings of your server.

Step 2: Check the port forwarding settings in the router.

Log into the router, then go to the port forwarding section; forwarding>virtual server. If you need assistance setting up port forwarding you can use one the following links for assistance: Green UI, Blue UI.

Step 3: Pay attention to the WAN IP address in status page

If there are still problems, please check the WAN IP of the router. Verify the router is getting a public IP address. If it is a private IP address, which means it's not enough to only open port on the TP-Link, you have to do the same setting on the modem router as well.

Please google if you don't know how to tell public IP Address or private IP Address.